• Nuclear Engineering and Technology
• /
• v.54 no.4
• /
• pp.1394-1405
• /
• 2022

The importance of ensuring the inherent safety and security has been more emphasized in recent years to demonstrate the integrity of nuclear facilities under external human-induced events (e.g. aircraft crashes). This work suggests a simulation methodology to effectively evaluate the impact of a commercial aircraft engine onto a dry storage facility. A full-scale engine model was developed and verified by Riera force-time history analysis. A reinforced concrete (RC) structure of a dry storage facility was also developed and material behavior of concrete was incorporated using three constitutive models namely: Continuous Surface Cap, Winfrith, and Karagozian & Case for comparison. Strain-based erosion limits for concrete were suitably defined and the local responses were then compared and analyzed with empirical formulas according to variations in impact velocity. The proposed methodology reasonably predicted such local damage modes of RC structure from the engine missile, and the analysis results agreed well with the calculations of empirical formulas. This research is expected to be helpful in reviewing the dry storage facility design and in the probabilistic risk assessment considering diverse impact scenarios.

• Nuclear Engineering and Technology
• /
• v.53 no.2
• /
• pp.455-465
• /
• 2021

The Molten Salt Reactor (MSR), one of the six advanced reactor types of the 4th generation nuclear energy systems, has many impressive features including economic advantages, inherent safety and nuclear non-proliferation. This paper introduces a system analysis code named TREND, which is developed and used for the steady and transient simulation of MSRs. The TREND code calculates the distributions of pressure, velocity and temperature of single-phase flows by solving the conservation equations of mass, momentum and energy, along with a fluid state equation. Heat structures coupled with the fluid dynamics model is sufficient to meet the demands of modeling MSR system-level thermal-hydraulics. The core power is based on the point reactor neutron kinetics model calculated by the typical Runge-Kutta method. An incremental PID controller is inserted to adjust the operation behaviors. The verification and validation of the TREND code have been carried out in two aspects: detailed code-to-code comparison with established thermal-hydraulic system codes such as RELAP5, and validation with the experimental data from MSRE and the CIET facility (the University of California, Berkeley's Compact Integral Effects Test facility).The results indicate that TREND can be used in analyzing the transient behaviors of MSRs and will be improved by validating with more experimental results with the support of SINAP.

• Nuclear Engineering and Technology
• /
• v.53 no.2
• /
• pp.386-392
• /
• 2021

MACCS (MELCOR Accident Consequence Code System), WinMACCS, and MelMACCS now facilitate a multi-unit consequence analysis. MACCS evaluates the consequences of an atmospheric release of radioactive gases and aerosols into the atmosphere and is most commonly used to perform probabilistic safety assessments (PSAs) and related consequence analyses for nuclear power plants (NPPs). WinMACCS is a user-friendly preprocessor for MACCS. MelMACCS extracts source-term information from a MELCOR plot file. The current development can combine an arbitrary number of source terms, representing simultaneous releases from a multi-unit facility, into a single consequence analysis. The development supports different release signatures, fission product inventories, and accident initiation times for each unit. The treatment is completely general except that the model is currently limited to collocated units. A major practical consideration for performing a multi-unit PSA is that a comprehensive treatment for more than two units may involve an intractable number of combinations of source terms. This paper proposes and evaluates an approach for reducing the number of calculations to be tractable, even for sites with eight or ten units. The approximation error introduced by the approach is acceptable and is considerably less than other errors and uncertainties inherent in a Level 3 PSA.

• The Korean Journal of Emergency Medical Services
• /
• v.25 no.3
• /
• pp.163-178
• /
• 2021

Purpose: This study explored a plan for improving the overall preventive activity of Korean Citizen-Corps-Active-in-Disaster (CAIND). Methods: The study used the documentary survey and the technical approach methods. This way, detailed information regarding civil anti-disaster organizations was found in scholarly monographs, specialty publications, and master's/doctoral dissertations. It further utilized the statistical yearbooks between 2015 and 2018 from the Korean Ministry of Public Administration, Security, and Fire Service, and the National Statistical Office, to discover practical problems through a statistical analysis. Volunteer activities being inherent, related issues were reviewed at the same time to for purposes of clarifying the characteristics of disaster prevention activity by CAIND. Results: The study provided four major suggestions for improvement. First, the quota management system of Korean CAIND considering the characteristics of rural areas should be supplemented. Second, the education and training systems of Korean CAIND should be established to satisfy regional conditions. Third, management members' readership competency in operating organizations, including that of the Korean CAIND captain in charge, should be strengthened. Fourth, the reward system for Korean CAIND activities should be improved. Conclusion: In the future, the results of this study are expected to be utilized as a basic data to develop Korean CAIND.

• Nuclear Engineering and Technology
• /
• v.54 no.5
• /
• pp.1560-1569
• /
• 2022

Liquid fueled molten salt reactors (MSRs) have seen renewed interest because of their inherent safety features, higher thermal efficiency and potential for efficient thorium utilisation for power generation. Thorium fluoride is one of the salts used in liquid fueled MSRs employing Th-U cycle. In the present study, ThF₄ was prepared by hydro-fluorination of ThO₂ using anhydrous HF gas. Process parameters viz. bed depth, hydrofluorination time and hydrofluorination temperature, were optimized for the preparation of ThF₄ in a static bed reactor setup. The products were characterized with X-Ray diffraction and experimental conditions for complete conversion to ThF₄ were established which also corroborated with the yield values. Hydrofluorination of ThO₂ at 450 ℃ for half an hour at a bed depth of 6 mm gave the best result, with a yield of about 99.36% ThF₄. No unconverted oxide or any other impurity was observed. Rietveld refinement was performed on the XRD data of this ThF₄, and Chi2 value of 3.54 indicated good agreement between observed and calculated profiles.

• Nuclear Engineering and Technology
• /
• v.56 no.3
• /
• pp.907-915
• /
• 2024

Various core designs with multi-batch fuel management (FM) are proposed and optimized for an innovative small modular reactor (iSMR), focusing on enhancing the inherent safety and neutronic performance. To achieve soluble-boron-free (SBF) operation, cylindrical centrally-shielded burnable absorbers (CSBAs) are utilized, reducing the burnup reactivity swing in both two- and three-batch FMs. All 69 fuel assemblies (FAs) are loaded with 2-cylindrical CSBA. Furthermore, the neutron economy is improved by deploying a truly-optimized PWR (TOP) lattice with a smaller fuel radius, optimized for neutron moderation under the SBF condition. The fuel shuffling and CSBA loading patterns are proposed for both 2- and 3-batch FM with the aim to lower the core leakage and achieve favorable power profiles. Numerical results show that both FM configurations achieve a small reactivity swing of about 1000 pcm and the power distributions are within the design criteria. The average discharge burnup in the two-batch core is comparable to three-batch commercial PWR like APR-1400. The proposed checker-board CR pattern with extended fingers effectively assures cold shutdown in the two-batch FM scenario, while in the three-batch FM, three N-1 scenarios are failed. The whole evaluation process is conducted using Monte Carlo Serpent 2 code in conjunction with ENDF/B-VII.1 nuclear library.

• International conference on construction engineering and project management
• /
• 2024.07a
• /
• pp.33-40
• /
• 2024

Off-site construction (OSC) is an architectural approach involving the prefabrication of building structures, components, parts, and equipment in a factory, followed by transportation to the construction site for assembly and installation. This method is particularly suitable for buildings with simple, repetitive structures and straightforward processes, such as hospitals, hotels, and schools. However, the inherent prefabrication characteristic has led to a widespread negative perception among the general public, resulting in significant resistance, especially from parents, concerning educational buildings utilizing OSC. In response, this study targeted users currently employing OSC in institutional buildings to analyze critical perception factors and derive avenues for enhancing the activation of OSC methods. The survey, categorized into seven factors, revealed that safety factors received the most positive responses, while social factors were identified as the most negatively perceived. The analysis of improvement requirements for OSC indicated that addressing issues related to hazardous material exposure and improving air quality are crucial in the equipment and eco-friendly aspects. In terms of design and usability improvement, maintaining harmony with the surrounding environment was identified as essential. Ultimately, this study anticipates the activation of OSC through the analysis of user perceptions and improvement suggestions for each OSC factor.

• Journal of the Korean Institute of Gas
• /
• v.13 no.1
• /
• pp.14-20
• /
• 2009

As the consumption of LNG has increased, the capacity and number of LNG facilities are getting bigger and bigger. Such circumstances supports the need for a dedicated risk analysis model to help review and check major issues of the safer construction and operation of LNG storage facilities systematically. Therefore this study suggests an appropriate risk analysis model that enables us to evaluate hazards of LNG storage facilities more easily and systematically, and then to use its result in siting, design and construction stages of the facilities. ill order to develop the model, lots of existing studies and domestic and foreign codes and standards were fully reviewed and a series of case studies also were carried out. The suggested model consists of 4-stage evaluations: in selecting a site, in determining a layout, in designing and constructing the facilities, and in operating them. This model also suggests the weather condition necessary for estimating the consequence of accident-scenarios, and the easy, systematic approach to the analysis of their probability. We expect that the model may help secure LNG storage facilities' inherent safety in determining their site and layout.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.22 no.2
• /
• pp.368-377
• /
• 2021

Plum is a typical fruit that is consumed processed rather than raw. In this study, we manufactured one of the processed foods, viz., plum Jangachi. In this process, the manpower-dependent seed separation and flesh cutting operations were automated by mechanizing, thereby altering the manufacturing process. Quality and Safety were assessed through microbial evaluation, analysis of color, and detection of preservatives in the plum Jangachi. Preference factors were identified through sensual evaluation. When compared with other plum Jangachi currently available in the market, our product was determined to contain 2.7±0.1 Log CFU/g total aerobic bacteria, which is slightly higher than the average of other products. This was not surprising, as the figures are due to the inherent characteristics, which were determined to be lower as compared to other commercial plum Jangachi. Other coliforms, tar dyes, and preservatives were undetected, thereby conferring satisfactory Quality and Safety. In general, there was no statistical difference in the sensual evaluation and appearance; overall, our product received better feedbacks than products on the market. Taken together, our results provide a foundation for applying the mechanization of plum-processed foods, thereby promoting the local economy in the main production area, and overall characteristics obtained are regarded sufficient in terms of market competitiveness.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.26 no.7
• /
• pp.798-809
• /
• 2020

Evidence-based policymaking and assessments for scientific administration have increased the importance of statistics (data) utilization. Statistics can explain specific phenomena by providing numerical values and are a public resource for national decision making. Due to these inherent attributes, statistics are utilized as baseline and base data for government policy determinations and the analysis of various phenomena. However, compared to the importance, the role of statistics is limited, and statistics are often used as simple abstracts, produced mainly for suppliers, not for consumers' perspectives to create value. This study explores the statistical data and other attributes that can be utilized for policies or research to address the problems mentioned above. The baseline statistical data used in this study is from the Maritime Distress Accident Statistical Yearbook published by the South Korean Coast Guard, and other additional attributes are from text analyses of vessel casualty situation reports from the South Korean Maritime Police. Collecting 56 attributes drawn from the text analysis and executing an EDA resulted in 88 attribute unions: 18 attribute unions had a satisfactory significance probability (p-value < .05) and a strong correlation coefficient above 0.7, and 70 attribute unions had a middle correlation. (over 0.4 and under 0.7). Additionally, to utilize the extra attributes discovered from the EDA politically, a keyword analysis for each detailed strategy of the disaster Preparation basic plan was executed, the utilization availability of the attributes was obtained using a matching process of keywords, and the EDA deducted attributes were examined.